PROJECT SUMMARY/ABSTRACT In September 2017, Hurricane Maria hit the island of Puerto Rico and wreaked havoc throughout the island, making it the most destructive storm in recorded history. The island's residents were still recovering from Hurricane Irma, which hit two weeks prior. For months after Maria, many communities lacked essential services and resources, such as access to electricity, potable water, safe roads and bridges, healthy foods, and medical care. Indeed, eight months later there are still communities lacking these services and resources. The extent of the damage, which impacted all residents regardless of geography or poverty status, and the fragile state of the Puerto Rican economy led to an institutional recovery response that was unprecedentedly slow and insufficient. The confluence of these factors created substantial population risk for psychiatric and substance use problems, particularly among those with a history of psychopathology. Few studies have examined the longitudinal development and exacerbation of psychiatric and substance use disorders before and after a natural disaster using the same representative sample. We have the unique opportunity and advantage of a preassembled cohort based on an island-wide representative sample stratified by the eight health regions of Puerto Rico. The cohort, which consists of 3,062 Puerto Ricans, ages 18-64 years, was surveyed from May 2014 to June 2016, one year before Maria hit the island. All lifetime and 12-month psychiatric and substance use disorders were assessed in this cohort using the World Mental Health- Composite International Diagnostic Interview (WMH-CIDI Version 21). We propose a second wave of assessments with a focus on anxiety, trauma-related, depressive, and substance use disorders, and suicidality. Using the National Institute of Minority Health and Health Disparities Research Framework and the Resilience Activation Framework of Abramson and colleagues, we will address four specific aims: (1) estimating the change in prevalence of psychiatric and substance use disorders from pre- to post-hurricane, (2) understanding the mechanisms that lead to increased psychopathology, including institutional response and recovery efforts and post-disaster stressors, (3) identifying the personal, family and neighborhood factors that lead to resilience among those who did not have psychopathology post-Hurricane Maria, and (4) understanding the effects of institutional response and recovery efforts on psychopathology across the eight health regions that vary in geography and levels of hurricane impact. The project is innovative in providing unique estimation of the longitudinal development and exacerbation of psychopathology pre- and post- hurricane, and, in examining unique mediators, particularly institutional response and recovery failures. It is also innovative in focusing on different levels (i.e.,personal, family, neighborhood) of factors that lead to individual resilience in the face of a major natural catastrophe in an economically struggling territory.